Beta-Ga2O3 Crystal Growth Using Low-Defect Plate Seed
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Solution Overview
Problem
The existing methods for growing β-Ga2O3 single crystals, such as the EFG method, often result in twinning or partial polycrystallization when expanding the shoulder, leading to a deterioration in crystal quality, especially when using wide plate-shaped seed crystals.
Innovation Solution
A method involving the use of a plate-shaped seed crystal with a defect density not exceeding 5×10^5/cm², grown in the b axis direction without shoulder expansion, utilizing an EFG crystal manufacturing device with a crucible and die configuration to control crystal orientation and prevent thermal impact, ensuring high crystal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the shoulder of the Ga2O3 single crystal is expanded during growth, then the width of the crystal is increased, but the crystal is likely to be twinned
Solution Approach 1:
The invention uses a plate-shaped seed crystal with a width larger than that of conventional seed crystals. By preparing the seed crystal in advance with the desired wide plate shape, the crystal can grow horizontally without requiring shoulder expansion during the growth process, thereby avoiding twinning while achieving the desired crystal width
Solution Approach 2:
Instead of expanding the shoulder during crystal growth to increase width (conventional approach), the invention inverts the approach by using a wide plate-shaped seed crystal from the beginning and allowing the crystal to grow horizontally without shoulder expansion, thus achieving width increase without compromising crystal quality
2Loss of time
If a plate-shaped seed crystal having a wide width is used to omit the expanding process, then the crystal growth time is reduced, but the grown crystal is subject to partial polycrystallization or deterioration in crystal quality
Solution Approach 1:
The invention changes the parameter of seed crystal width to be larger than conventional seed crystals (specifically, a plate-shaped seed crystal with a width of 5 mm or more). This parameter change allows the crystal to grow horizontally without shoulder expansion, reducing growth time while maintaining high crystal quality by preventing partial polycrystallization through careful control of other growth parameters
3Area of moving object
If a plate-shaped seed crystal with a wide width is used, then the crystal width is increased, but the crystal quality deteriorates due to partial polycrystallization
Solution Approach 1:
The invention prepares a plate-shaped seed crystal in advance with a width of 5 mm or more. By having the wide plate shape already established in the seed crystal before growth begins, the crystal can maintain its wide dimensions throughout growth without requiring shoulder expansion, thus avoiding the partial polycrystallization that would otherwise occur
Solution Approach 2:
The invention changes the seed crystal width parameter to 5 mm or more (compared to conventional narrower seed crystals). This parameter change, combined with controlling the horizontal growth rate to be 0.5 mm/h or more, enables the crystal to achieve wide dimensions while maintaining high crystal quality and avoiding partial polycrystallization
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the growth of high-quality, plate-shaped β-Ga2O3 single crystals with reduced polycrystallization and twinning, maintaining high crystal quality even with wide seed crystals, achieving defect densities suitable for LED substrates.
Implementation Method 1
a die 14 having a slit 14A, which raises the Ga2O3-based melt 12 by capillarity phenomenon to an opening part 14B of the slit 14A
Implementation Method 2
By lowering the seed crystal 20 so as to be brought into contact with the Ga2O3-based melt 12 that ascends through the slit 14A of the die 14 to the opening part 14B by capillarity phenomenon, and pulling up the seed crystal 20 brought into contact with the Ga2O3-based melt 12, a plate-shaped β-Ga2O3-based single crystal 25 is grown
Data Source
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AI summary
Provided is a method for growing a β-Ga2O3 single crystal, which enables the production of a plate-like β-Ga2O3 single crystal having high crystal quality. In one embodiment, a method for growing a β-Ga2O3 single crystal employing an EFG method is provided, said method comprising the steps of: bringing a plate-like seed crystal (20) into contact with a Ga203 melt (12), wherein the plate-like seed crystal (20) comprises a β-Ga2O3 single crystal having a defect density of 5x105 /cm2 or less in the whole region; and pulling up the seed crystal (20) to grow a β-Ga2O3 single crystal (25).